The present invention relates generally to mobile terminals usable in radiocommunication systems and, more particularly, to interfaces between mobile terminals and auxiliary devices and features.
The cellular telephone industry has made phenomenal strides in commercial operations in the United States as well as the rest of the world. Growth in major metropolitan areas has far exceeded expectations and is rapidly outstripping system capacity. If this trend continues, the effects of this industry""s growth will soon reach even the smallest markets. Innovative solutions are required to meet these increasing capacity needs as well as maintain high quality service and avoid rising prices.
Mobile terminals, sometimes more commonly referred to as mobile phones, are also changing to suit subscriber demand and support an increasing array of services and features. For example, some consumer groups have found xe2x80x9cflipxe2x80x9d phones to be desirable, i.e., those mobile terminals wherein a portion of the housing can rotate between open and closed positions. Hands-free sets are also quite popular, which devices permit users to communicate wirelessly using their mobile terminals while also keeping their hands free for other tasks. As additional auxiliary devices or features become available, terminal designers must be able to interface those devices with the mobile phone, both mechanically and, at least in some cases, electrically. This poses various challenges.
For example, in the case of the flip phone, it may be desirable for the terminal""s processor to know when the flip portion of the housing is open, so that other functions associated with the terminal, e.g., the display""s backlighting, can be selectively actuated and the terminal can be otherwise activated without any other action required on the part of the user. Similarly, for users employing hands-free sets, it may be desirable to provide these users with a mechanism to enable them to activate the phone, e.g., to receive a call, without having to press a button on the terminal itself, which terminal may be disposed in an inconvenient pocket of the user.
To provide these, and other features, to mobile terminals typically requires some type of signaling between the auxiliary device and the terminal of the processor. To accommodate this signaling, preferably without adding complexity or cost to the mobile terminal, is a further object of the present invention.
These, and other, challenges are addressed by exemplary embodiments of the present invention. According to a first exemplary embodiment, a microphone provided in a mobile terminal is connected to a current source when the flip portion of the mobile terminal is open and is disconnected from the current source when the flip portion of the phone is closed. The mobile terminal can then infer the position of the flip portion of the housing, e.g., opened or closed, based upon the state of the microphone""s current supply circuit, for example by detecting the current flowing through the circuit or a voltage drop across a supply resistor.
According to a second exemplary embodiment of the present invention, an on-hook/off-hook button can be provided to a hands-free accessory without increasing a number of signal lines/connections between the hands-free accessory and the mobile terminal. This can be accomplished, for example, by connecting the on-hook/off-hook button to a switch in the microphone signal line. In one embodiment, the switch selectively creates an open in the microphone signal line, which can be detected by the mobile terminal, thereby resulting in an off-hook condition. In another embodiment, the switch selectively shorts the microphone signal line, which short can be detected by the mobile terminal to thereby result in an off-hook condition.
According to yet another exemplary embodiment of the present invention, an interface between a mobile terminal and other auxiliary or accessory devices can be generalized to accommodate either digital or analog signaling without an increase in the number of pins/signal lines associated with the interface.